Internal combustion engines exhaust a complex mixture of air pollutants. These air pollutants are composed of solid particulate matter and gaseous compounds including nitrogen oxides (NOx). Due to increased attention on the environment, exhaust emission standards have become more stringent and the amount of solid particulate matter and gaseous compounds emitted to the atmosphere from an engine is regulated depending on the type of engine, size of engine, and/or class of engine.
One method that has been implemented by engine manufacturers to comply with the regulation of these engine emissions is exhaust gas recirculation (EGR). EGR systems recirculate exhaust gas by-products into the intake of an internal combustion engine. The exhaust gas, which is redirected to a cylinder of the engine, reduces the concentration of oxygen therein, thereby lowering the maximum combustion temperature within the cylinder. The lowered maximum combustion temperature slows the chemical reaction of the combustion process, thereby decreasing the formation of nitrogen oxides. In addition, some of the particulate matter entrained in the exhaust is burned upon reintroduction into the engine cylinder to further reduce the exhaust gas by-products.
Before the exhaust gas enters the engine cylinders, it must first be mixed with air and cooled to the proper temperature. To cool the mixture of air and exhaust, the mixture is directed through a heat exchanger. While in the heat exchanger and at locations downstream of the heat exchanger, moisture previously entrained in the air and exhaust mixture condenses on the relatively cool walls of the heat exchanger. Because of the presence of sulfur and nitrogen oxides in the exhaust, the condensate can be corrosive and potentially damaging to the heat exchanger, downstream passageways, and the engine. The condensate may also cause premature wear of the engine due to the condensate's mechanical interactions with the piston, piston rings, and engine valves as the pistons reciprocate and the valves open within the cylinders.
One way to minimize the damage caused by condensation is disclosed in U.S. Pat. No. 6,748,741 (the '741 patent) issued to Martin et al. on Jun. 15, 2004. Specifically, the '741 patent discloses a charge air condensation separation system for a turbocharged engine employing EGR. The separation system includes a turbocharger having a compressor providing charge air, with a charge air cooler connected to the compressor to cool the charge air. A charge air delivery duct is connected to an outlet of the charge air cooler, and a toroidal trap having an annular inlet is disposed in the charge air delivery duct. A swirl generator may be used to urge the condensate toward the walls of the charge air duct for subsequent trapping. The toroidal trap has a sump for collecting condensation internal to the toroidal trap. A drain line for removing condensation from the sump for expulsion to the atmosphere is connected to the trap, and a pump or other device for overcoming a pressure differential in the drain line is employed in certain embodiments.
Although the separation system of the '741 patent may help to minimize damage resulting from condensation-caused acid, it may be limited and result in poor engine emissions. Specifically, although condensate from the charge air may be removed from the system, condensate from the recirculated exhaust may be unrestricted. That is, moisture from the recirculated exhaust flow may still be allowed to condense within the duct work of the engine and, because the separation system only removes condensate from the charge air, the condensed liquid from the recirculated exhaust flow may travel unrestricted into and damage the engine. And, because the acid solution is mainly caused by sulfur compounds and nitrogen oxides in the recirculated exhaust flow, the condensate from the exhaust may be more damaging than the condensate from the charge air. Further, it has been shown that the introduction of well dispersed or atomized (i.e., not condensed) non-combustible fluid into the combustion chamber of an engine during operation may be helpful in reducing the amount of NOx produced by the engine. Thus, because the separation system of the '741 patent removes the fluid from the charge air flow rather than homogeneously redispersing it into the air flow, the NOx production of the engine may be excessive.
The disclosed condensation reduction device is directed to overcoming one or more of the problems set forth above.